Ozone control for precipitators



Feb. 6, 1940. w PENNEY I 2,189,614

OZONE CONTROL FOR PRECIPITATORS Filed May 6, 1938 2 Sheets-Sheet 1 l6 A f/ g. 9

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- v ziinize I I 3 v I 09568 45 47 n /4 a @K WITNESSES: r g lNVENTOR @W/CM' Gay/0rd 14/ Penney @Mm/ I BY v ATTORNEY Feb. 6, 1940.- w PENNEY 2,189,614

QZONE CONTROL FOR PRECI PITATORS Filed May 6, 1958 l ZSheets-Sheet 2 I; I 15% i 54 Fresh Air I INVENTOR- Gay/0m 14/. Penney BYwd v ATTORNEY WITNESSES: @u.

- Patented Feb. 6, 1940 i Q I I UNITED STATES PATENT OFFICE v 2,189,011 v ozoNn coN'mor. Fon raacrrrra'roas Gaylord W. Penney, Wilkinsburg, P2,, ascignor to Westinghouse Electric a Manufacturing Company, East Pittsburgh, Pa a corporation of Pennsylvania Amiu muon my 6, 1938. Serial No. 206,380

' 12 Claims. (Cl. 183-7) In application Serial No. 45,070, irlled Oct. 15, Usuallythe number of recirculations per unit 1935 by myself and assigned to the Westingtime is suflloiently low or the ozone generated house Electric c Manufacturing Company, and d i g each passage oi eci t ir through which has matured into Patent 2,129,783, granted the cleaner is sufficiently absorbed in the space 6 September 13, 1938, I disclose an electrostatic being conditioned that the unit may be operated 5 air cleaner for precipitating all kinds of foreign at a high eiiiciency and a'r'elatively large amount particles from air or, any other gaseous fluids. oi ozone generation per passage is permissible.

-My precipitator operates along the general prin- However, in rare cases a combination of citciple of chargin or idnlzing th 1 parcumstances may exist wherein the limits of perticles in the air ,and collecting them by eleotromissible ozone content are so rigid, the frequency .10 static depositionl In my \particular 7 preclpitator f p es recirculated is sumeienfly at.

I pass air to an ionizing zone in win ch zone th or the sensitivity of the place being air condin particles-such as dust and tube like are tioned to even minute ozone content is so deliiven electric charges. The air c nti into cate that exceptional precautions must be taken a collector zone which consists usual lly of a plu- P t t Ozone, content exceeding the 9 y of parallel plates m' m al'gernmte harges, hibitive limits which may be reached by the The charged particles pas sing between the plates cumulative increase of the ozone content as the are attracted to a plate of opposite charge and air is repeatedly recirculated. adhere thereto, the cleam air continuing through 0n the other hand, a combination of circumgothe collecting zone, j stances may exist whereinthe limits of ozone One of th factor {MRI-mining an geptable content 'are moderate so that with a large perprecipitator for air c'lea ning is the amount of centage of fresh air passing through the cleaner ozone created or gener t, id i th ,1;- as t l a relatively large but harmless amount of ozone flows through the diil'erfl t zones, The ozone is permissible; but when, under similar circumcreated is usually a tunoiiion oi the voltage betanc'es the air being conditioned has a large per- 25. tween the ionizing element s for a parti ular co centage of recirculation, the tendency toward struction thereof. Howe Br, 11; is always deskcumulative increase of ozone content may be able to operate a preei it ltor at the 1 maximum great enough also to require exceptional precau- Veltflge which does not g l-ve an objlectionable tions to preventan excess of ozone content from ozone content for the reaso; a l that the maximum accumulating. .fiortunately, when all fresh air so cleaning efliciency is thereby obtained for a given is being used, a high voltage with resultant high precrpitator. 1 emciency can be employed with no cumulative Where a large proporti 1 1 the nm increase of ozone. When recirculated air is cleaned is fresh air, the i reoipitator may be added, then for a given volume of air being 36 iusted to operate at a 'vojlltage for maximum cleaned the content of the ioreign particles is on cleaning with a minimum. 0; t ozone generation. necessarily less since some of the air has already Usually the ozone generated 1 s so negligible that been cleaned. The precipitator may, therefore. ipzgtaware of no instanr 1 n which a cleaner be o erated at a slightly lower voltage and em- I ng 310118 the principle is Set forth in my ciency which will not, however, lower the overall z i application as not 3 been Satisfactory or resultant cleanliness of the air, but which w gsg g gzg g g rigid (it ppeleting f will decrease the amount of ozone generated. 0mm; in large n i1 f t i and n s; Accordingly, it is proposed to regulate the ionizth 1 y a 1 er a amom ing voltages, and where required, the plate volte a r to be cleaned has a u eady been cleaned a e i r t m m0 nt f 1 late! and is recirculated throu h no reci itatOr with g 0 e a rec g i f p p i d to the amount of fresh air assthe addition of som fr h ilr. In some parf as compare p ticular cases all the air p rss ing through the mg through the cleaner precipitate], may be air the b E as already been It is accordingly an object of my invention to lower the possibility of excessive ozone accumucleaned thereby. w tpitator is used with recirculated air it 8 MB apparent that lation in system employing recirculating or Dre- 50 viously cleaned air.

the ozone genera, of the air through the unit? 111253 221; $523 fi therwise, is ,It is a further object of my invention autoadded to the ozone generated eagh successive matlcally to minimize the possibility of excessive a e, and in this manne 1 the ozone content ozone accumulation in re-circulatlng systems by may cumulatively increase. controlling the ionizing voltage as a function of 55 the proportion of re-circulating air to the total air intake.

In most re-circulating systems, dampers" are inserted in the fresh air conduit and the recirculating air conduits, these dampers being controlled in response to some physical condition. Thus, it is not uncommon to have the inside temperature, or outside temperature, or a combination of both, control the dampers. Again, and particularly in auditoriums or entertainment houses, the dampers may be controlled in response to the number of people therein. Other factors are frequently taken into consideration as is well known. In this system which I now propose, I can control the ionizing voltage or I can control the collector plate voltages, or both, from the dampers which are controlled by such physical factors, or may even control the voltages directly by the various physical factors themselves.

Many other objects and novel features of myinvention and equivalents thereof will be apparent from the following description, in the drawings of which I symbolically represent in:

Figure 1 one embodiment wherein the voltage is controlled by the position of the dampers;

Fig. 2 a modification of Fig. 1 in which individual voltage controls are applied for the ionizing and collector zones;

.Fig. 3 a modification in which the voltage is varied directly by the physical factor which controls the dampers;

Fig. 4 my invention separate transformers lector zones;

Fig. 5 still another modification of voltage control.

Referring to Fig. 1, the precipitator has an ionizing zone shown symbolically at I and a col lector zone shown symbolically at 2. For greater details of a preferred construction of these parts, reference may be had to my aforesaid application.

Briefly, the ionizing zone includes ionizing wires 4 and cooperating rods 5 having a potential therebetween and the positely disposed parallel plates 4 and I, the electrostatic field and voltage differentials for which maybe created by any appropriate electrical circuit. To illustrate the principle of my invention, I show a circuit which includes commercial power mains I across which is connected transformer Q. Transformer 9 is preferably made of the high leakage type as a matter of safety and comprises a primary winding l0 and a secondary winding l4. One terminal I! of the secondary winding is connected through a high resistance to the plate of any appropriate rectifier tube Ii, the filament or cathode of this tube being connected tothe ionizing wires 4.

applied to a unit having for the ionizing and col- "lhe cathode of the tube It also connects to one terminal ll of a condenser IS, the other terminal ll of which is connected to the other terminal of the transformer secondary I4. A condenser 24 has one of its terminals 25 also connected to the secondary end terminal 20, the other terminal 26 of the condenser being connected through a high resistance to the plate of a secondary rectifier tube 21. The cathode of this rectifier tube connects to an intermediate point 2' of the secondary l4.

As is shown in Fig. 1, terminal 26 is grounded which necessarily grounds all circuits conducted thereto at this point. If desired, leakage rea means of collector zone includes opsistances may be connected across the condensers l8 and 24, respectively.

The parallel collector plates 4 are conductively joined together and to the terminal 2|, the opposite plates 1 being grounded. Rods 5 in the ionizing zone may all be grounded, but I desire to ground all but one of them, the latter being grounded through a neon tube 24 in parallel with a resistance 30, this neon tube serving as an indicator.

The circuits thus far described are substantially-the equivalent of those disclosed in my aforesaid application and operate in the same way; that is, a positive potential is applied to the ionizing wires 5 and a positive potential is applied to the collector plates 6,-these potentials being determined by'the particular construction employed so that .a maximum of cleaning is obtained with a minimum of ozone generation.

Fresh air duct II and clean or re-circulated air duct 32 merge into the common main supply air duct 33' for the cleaner unit. The fresh air duct has its inlet opening to the outside atmosphere, while the re-circulated air duct has its inlet opening to the premises being air conditioned. This structure is well known to the art and may follow any of a number of forms (not shown). Within the branch ducts ii and I2 are dampers 33 and M, respectively, for controlling the proportion 01. air each branch duct is to supply to the main duct 33'. The positions of the dampers may be controlled by any appropriate means which 1. have shown symbolically as comprising a wire or the like I! connected to the ends of operating devices for the dampers and positioning them. It is obvious that these wires may be external to the ducts and may be connected to elements integral with the dampers as for example the crank arms shown. The wire 35 has a means represented by the weight 30 tending to position the dampers with the fresh air duct fully opened and the clean air duct fully closed. By means of a mechanism 31, which may be a counter for counting the number of persons in the premises being supplied with cleaned air, or a temperature responsive device. or any device responsive to some physical factor involved in airconiditioning, the wire 38 is moved against the force of the weight It in accordance This movement of the wire will tend to close fresh air damper 3.3 and open the clean or re-- circulated air damper 34. Attached to the shaft of one of the dampers is a linkage system ll which moves in accordance with the movement of the dampers and, therefore, in accordance with the change in the physical factor aforesaid.

At the end of the linkage system 88 is a roller 39 moving in a cam groove 40 of a cam 41 attached to a movable voltage regulator arm 42, and preferably insulated therefrom. The arm 42 is pivoted at 49, and is in the main circuit supplying the primary ill of the transformer 9 and varies the number of turns of the primary as the linkage 38 changes its position. The cam groove 40 may follow any desired contour or ourvature, so that the voltages applied to the precipitating elements: of the cleaner unit may be in accordance with any values desired relative to the positions oi the dampers ll. In this manner, as the fresh air damper 33 is closed and the cleaned air damper 34 is opened, the number of turns in the primary may be increased, thereby decreasing the: potential across the ionizing wires 4 and the rods I, as well as the potential between the collector plates I and I.

In Fig. 2 I show wherein the secondary voltages may be controlled in accordance with the posi-.v tions of the dampers rather thanthe primary winding as shown in Fig. 1. By this construction I can independently vary the potentials in the ionizing zone and in the collector zone. The linkage I8, which is connected to move with the dampers, has a roller 39' moving in a cam groove 40 of a cam 4| attached to the voltage regulating arm 42'. Pivoted on the cam 4| is a link 43 having a roller 44 at one end thereof. This roller 44 moves in the cam groove 46 of a cam attached to voltage regulating arm 41. It is obvious that as the dampers move, the roller 8! will move in the cam groove 40' raising or lowering, as the case may be, the regulating arm 42' in any desired relationship determined by the shape of the cam groove 40'. Moreover, movement of the cam 4| causes the roller 44 to move latter. zone.

within its cam groove 45, the shape of this cam groove also being determined by the amount it is desired to vary the potential across the collector plates for given positions of the dampers. Usually, ;I prefer to vary the potential across the collector plates only to a slight degree, if at all, most of the voltage control being eifected in the ionizing zone, inasmuch as whatever ozone is created by the cleaning apparatus occurs in this In Fig. 3 I show symbolically wherein the position of voltage regulating arm 42 determining the number of turns in the primary winding I0 is controlled directly from the variable physical factor. Cam roller 39 is attached to a link 48, which in turn isattached to the wire 35 by means of a second wire 50. 'Manifestlyj if desired. the wire 50 may control the secondary voltages rather than the primary voltages in accordance with the showing of Fig. 2. I I In Fig. 4 I show the application of myinvention to a cleaning unit of higher capacity than that of Fig. 1. In this unit, separate transform ers 8i and 52 comprise sources of high potentials for the ionizing zones and collector zones. Movement of the dampers 33 and 34 by the physical factor moves the link 52', having roller I53 riding in the cam groove 54 of a cam 55 attached to the voltage regulating arm 42 for the primary 59 of the transformer ll. The movement of the cam 55 is transmitted to the link 56, which also has a roller 5.1 riding in cam groove 58 of a cam 60 attached to voltage regulating arm SI for the primary 62 of the transformer 52. This structure operates along the principles and in the manner of the previous figures, that is, movement of the link 52' in accordance with the movement of the dampers 33 and 34 causes roller 53 to ride in the cam groove 54 and position the regulating arm 42.

. At the same time, roller 51 rides in cam groove 68 positioning the regulating arm 6|. The movements of the regulating arms, of course, control the voltages between the electrodes of the ionizing zone and between the plates of the collector zone.

In Fig. 5 I show wherein I do away with the linkage and cams of the previous figures. Taps are brought from the primaries 59 and 82 and terminate in proximity to one of the dampersshown in Fig. 5 as damper 33. Moving with the damper is aregulating arm I sliding over two sets of contacts 84 for the primary 62, and. for the primary 59. As the arm 83 moves, the number of turns in the primary i9 and the number of the turns in theprimary l2 are obviously changed. I

ia the number of turns of the Howevenit may be observed that inv thefirst three positions of the arm 63 no change is made primary 6: so that no change is made in the potential across the collector plates.

The percentages of change in the two voltages, that is, the voltage across the ionizing elements anl the voltage across the collector elements, are not necessarily-the same. The principle is generally to reduce the plate voltage to give negligible current and to adjust the ionizing voltage, to give the necessary low-generation of ozone with high, cleaning efliciency. Thus, for example, I may start with standard conditions, that is, efficiency and microamperes per foot of ionizins wire when the unit is operating with a fresh air supply only. If. the current is now. reduced to one-half, I'thereby reduce the efficiency to 93%,, and the relative ozone generated to approximately ditions is, generated. However, .while the emciency of the unit is decreased with the two adjustments above described, the over-all cleaning actually increases as compared'to outdoor air.

' For examplestandard conditions with fresh air resulting in a 95% cleaning efllciency yields air 95% However/with one-half recirculation and an adiustment of the current to one-half its value, the

air in the premises is 96'/4%- clean. With threefourths recirculated air and one-fourth of the current the air in the premises is 97%% clean. This, of course. is due to the fact that the recirculated air has already been cleaned. These figures are only indicative of how my invention may be utilized and shows that the actual cleanliness of the room air can be made to improve with recirculation whilev preventing .an increase in the concentration of ozone. I

My invention is obviously susceptible to differs out forms and mechanical expedients for the control of the transformer secondary voltages. I fully contemplate the use of any electric telemetering system or self-synchronizing system or the like ior moving any of the regulating arms in accordance with the position of the dampers or directly in accordance with the variation in the physical factors determining the amount of permissible ozone generation- Moreover, in most instances, the ionizing potential only need be changed for it is in the ionizing zone, that the ozone is created except in rare instances. However, for each ionizing voltage'there is a maximum plate potential by which the maximum ciliciency of cleaning under particular conditions can be obtained. Accordingly, I have also shown wherein the voltage between the collector plates may be varied, if such be desired to give the maximum efliciency for the particular occasion.

It is obvious that many changes may be made within the spirit and scope of the novel system which I have introduced. Thus,1 for example, the separate ionizing and collector zones I have shown can be combined into a single zone, as is common in the art, and that other gaseous atmospheres can be substituted for "air" which I desire shall, therefore, be broadly construed. It is desired, therefore, that the appended claims be given the broadest constructionconsistent with their language and limited by the prior art.

I claim as my invention: i. In a system for cleaning air supplied to an clean in the premises supplied with this air. a

enclosure, an electrostatic precipitator having an air outlet to said enclosure, air inlet means to said precipitator comprising a and a duct for air from said enclosure, said precipitator having ionizing means through which the air passes, said ionizing means being of a type which inherently generates small amounts of ozone, and means to decrease the ozone generating power of said ionizing means in accordance with the relative amounts of air supplied to said precipitator by said ducts.

2. An air cleaning system comprising an electric precipitator having a plurality of electrodes for ionizing and collecting dust particles and the like, means to apply variable potentials between cooperative electrodes of said electrodes, said precipitator also having an air outlet means, a fresh air inlet and an electrostatically-cleaned air inlet, and means to control the air admitted through said inlets and said first named means.

3. An electrostatic precipitator comprising a plurality of electrodes for ionizing and collecting dust particles and the like, means to apply variable potentials between cooperative electrodes of said electrodes, an air inlet and outlet for said precipitator, said inlet having provisions for admitting fresh air and electrostatically cleaned air to said precipitator, and means responsive to the inlet amount of previously cleaned air relative to fresh air for controlling said first-named means whereby the ozone generation is controlled.

4.1m electrostatic precipitator for cleaning air for an enclosure comprising a plurality of electrodes for ionizing and collecting dust particles and the like, means to apply variable potentials between cooperative electrodes of said electrodes, an air outlet for said precipitator, a fresh air inlet for said precipitator, a recirculating air inlet for said precipitator, means to control the relative amounts of fresh and recirculating air and said first means whereby the ozone generation is controlled.

5. An electrostatic precipitator having a plurality of electrodes for ionizing and collecting dust particles and the like, means for applying variable potentials betweencooperative electrodes of said electrodes, an air outlet for said precipltator, a fresh air inlet for said precipitator, a recirculating air inlet for said precipitator, dampers for said inlets, and means responsive to the position of said dampers for controlling the first-named means whereby the ozone generation is controlled.

6. An electrostatic precipitaior for cleaning air for an enclosure having ionizing electrodes and collecting electrodes, means comprising a transformer and rectifier for applying a potential between said ionizing electrodes, means for applying apotential between said collecting elecduct for fresh all" trodes, and means to vary the potential applied to said ionizing electrodes by the first said means in response to variations of an external factor in said enclosure whereby the ozone generation is controlled.

'7. An electrostatic precipitator having ionising electrodes and collecting electrodes, means comprising a transformer and rectifier for app is potential between said ionizing electrodes, means for applying a potential between said 001 lecting electrodes, means to vary the potential applied to said ionizing electrodes by the first means, variable means to admit different proportions of fresh and electrostatically cleaned air to the precipitator, and means responsive to variations of the last-named means for controlling said third means whereby the ozone generation is controlled.

8. The apparatus of claim 5 wherein said last means operates upon the primary of said transformer.

9. The apparatus of claim 5 wherein said third means operates upon the primary of said transformer.

10. A precipitator comprising ionizing elec-. trodes and collector electrodes, means comprising a transformer and rectifiers for applying variable potentials between said ionizing electrodes, a second means comprising a transformer and rectifier for applying variable potentials between said collector electrodes, means to vary the potential applied to said ionizing electrodes, means to vary the potential applied to said collector electrodes, variable means to admit different proportions of fresh and electrostatically cleaned air to the precipitator, and means responsive to variation of the last said means for operating the said potential varying means but in different degrees whereby the ozone generation is controlled.

11. In .a system for cleaning air supplied to an enclosure, an electric precipitator having fa plurality of electrodes for ionizing and collect dust particles and the like, means to apply va able potentials between cooperative electrodes of said electrodes, means to supply said precipitator with electrostatically-cleaned air, and means to control the first said means in accordance with the amount of air supplied by the second named means.

12. In a system for controlling the ozone content of an enclosure supplied with air cleaned electrostatically, the method which comprises passing a mixture of fresh air and air from said enclosure through an electrostatic field, varying the proportions of said fresh air and air from said enclosure, and changing said field in accordance with the said proportions.

GAYLORD W. PENNIY. 

